This invention relates to a cathodic process for the electrodeposition of polymer powders. More particularly, it relates to such a process wherein the powders are coated with metal oxides or hydroxides.
The prior art includes cathodic electrodeposition processes which deposit a variety of types of polymers and micron-sized polymer powders blended with metal oxide, hydroxide and metallic powders. See U.S. Pat. No. 4,086,153--Ariga et al granted Apr. 25, 1978; U.S. Pat. No. 3,920,468--Brown et al, granted Nov. 18, 1975; U.S. Pat. No. 3,657,092--Fischer et al, granted Apr. 18, 1972; U.S. Pat. No. 3,575,909--Gilchrist, granted Apr. 20, 1971. Similar technology for electrodepositing magnetic layers is the subject of U.S. Pat. No. 3,647,661 Matsushita, granted Mar. 7, 1972. Generally, the ionic structure of the polymer is important so that it can be electrodeposited directly rather than relying on entanglement or entrainment for codeposition with, for instance, charged oxide particles. Published Japanese patent application 51-44540--Origa et al, of Nov. 29, 1976, codeposits resin particles which need not be charged along with charged metal oxide particles. U.S. Pat. Nos. 3,869,366--Suzuki et al, granted Mar. 4, 1975, and 4,208,261--Todoroki et al, granted June 17, 1980, both relate to electrocoating with a cationic binder resin and a nonionic resin powder disposed therein.
U.S. Pat. No. 4,122,060--Yallourakis, granted Oct. 24, 1978, and U.S. Pat. No. 4,251,426--McClure et al, granted Feb. 17, 1981, both relate to epoxy resin powder coating compositions. Both can be applied by a variety of techniques, but optimum electrocoating methods have not been available for their application due to the lack of appropriate electrical charges built into the polymers. These two patents are incorporated herein by reference.